Free Suduko

In May 1979 an issue of “ Dell Pencil Puzzles & Word Games”first printed a variation of Sudoku which mostly resembles the game which we are all now well acquainted with. Since then, due to its huge success, many have tried to offer numerous variations of the game, in order to make it more interesting, more attractive and even trickier.

For example, the graph theorist Gordon Royle has been “collecting” over 10.000 Sudoku games which follow the exact same rules as the ones one can find in almost every newspaper; what do all these games have in common? Well they all have only 17 givens (instead of the 18 a magazine-solver is used to). 17 is the minimum number of givens which lead to a single puzzle solution; of course this increases the game’s difficulty, but, trusts me, it’s all worth it!

Still not interested? Don’t worry. There are still many kinds of Sudoku-s waiting to be discovered.

Just check this one out: Diagonal Sudoku! Also called Sudoku X, this variation doesn’t have a minimal number of givens because it comes with a new restriction: the grid must be completed so that every row, column, three*three box and also the 2 main diagonals contain all the digits from 1 to 9 only once. This variation was invented by Walter Mackey, who allowed it to be published for the first time sometimes in the early 1990’s in “Dell Champion” magazine.

Consecutive Sudoku stirred up many spirits when it came to deciding what is the minimal number of givens. Graph theorists were surprised to say: one! In this game, all the tiny boxes where orthogonally adjacent boxes are to be filled in with consecutive digits are marked.

Some have rediscovered the beauty of Latin Squares. These are also called Geometry Sudoku-s. The odd thing about them is that irregular regions (geometric shapes) replace the three*three boxes. The shapes can be very funny, though!

Another variety of Sudoku (Number Place) which comes up with another innovation: instead of 9 digits, players are bound here to complete each three*three squares with 10: numbers from 0 up to 9. Obviously, some cells will contain two digits; these cells are marked, but come to think about it, an identical puzzle without marked cells would be a lot more difficult than a regular one, don’t you agree?

And that’s not all… there are also a lot of other fun Sudoku games like Magic Sudoku, Domino Sudoku, and even Sums Sudoku (you definitely ought to check this one, it’s great!). Well, what can I say folks, other than… Enjoy!